Wire feeding systems are commonly used for feeding welding wires from a supply source, for example a container in which a significant amount (up to more than one ton) of welding wire is being stored, to a point called welding arc where the welding wire is being deposited through a welding torch, with the purpose of joining metal parts.
In robotic and automated applications, which are designed to maximize the productivity, it has become a common practice to utilize large bulk packs containing from few hundred kilograms to more than one ton of welding wire. In the initial, and now obsolete automatic setups, the packs were placed on rotating turntables and the rotational movement of the pack helped offset the tension naturally building on the wire during its payout. For safety and practical reasons, like the shop floor space limitation in plants, the past two decades have seen a wide use of the so called “twist-free” “torsionless” welding wires being paid out from a stationary pack and the wire being deposited into the container through a special winding process. The twist-free winding process has been known for quite some time.
The welding wire is drawn from a manufacturing process and runs over rollers, is pulled along by a capstan and is fed into a rotatable cylindrical tube comprising an opening at the bottom or along the cylinder adjacent to the bottom. The wire extends through the tube and out the opening, whereupon it is placed into the storage container.
The tube protrudes into the storage container and rotates about an axis parallel to the storage container axis. The wire is fed into the tube by the capstan and at a rotational velocity different than the rotational velocity of the tube. A ratio between the rotational velocities of the tube and the capstan defines a loop size diameter of the wire within the storage container.
The twist-free winding however is not a simple process and it can be negatively affected by a number of variables, like the columnar strength of the wire, its diameter or its surface condition. In particular, aluminum welding wires are difficult to become plastically deformed and pre-twisted, because of their elasticity; moreover their rougher surface condition increases the friction and complicates the feeding through the conduit guiding the wire into the pack. Although the twist-free winding machines of most recent construction are provided with a variety of controls and adjusting options, it is virtually impossible to continuously and dynamically compensate the inevitable wire deformations and defects. If the twist-free torsion-free winding machine is unable to completely eliminate the residual wire tension while laying it down into the container, this residual tension increasingly accumulates on the wire during the payout process until the wire is so loaded that it will eventually tangle and jam inside the pack and cause an unwanted interruption of the welding process. In the case of automatic and robotic welding, unwanted weld interruptions caused by wire tangles can be extremely expensive and can impact the complete production line with costly production downtime, bad welds and weld repairs.
It is therefore an object of the present invention to provide a system that can help minimize and even eliminate the accumulation of tension on the wire during its payout from the bulk pack.
It is a further object of the present invention to provide a system that can help improve the safety around the wire bulk pack, allow a visual access of the wire during its payoff and protect the wire itself from possible contamination.